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Melissa Mathieson, 18, was strangled at a Bristol residential home

A man with "abnormal sexual drive" has been convicted of murdering a woman at a residential home providing special care for adults.

Jason Conroy, 18, strangled Melissa Mathieson, also 18, last year at the Bristol centre where they both lived.

Conroy had indicated as a child he wanted to have sex with a dead woman, the trial at Bristol Crown Court heard.

Conroy had denied murder, but had admitted manslaughter on the grounds of diminished responsibility.

The manslaughter plea was not accepted by prosecutors.

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The jury was told Jason Conroy showed "abnormal sexual drive" from a young age

Shortly before the attack Miss Mathieson had told care staff at the Alexandra House residential home she was being stalked and Conroy was making her feel scared.

According to its website, Alexandra House specialises in care for adults with Asperger syndrome and autistic spectrum disorders.

An independent review into the case has been commissioned by the Bristol Safeguarding Adults Board.

The Mathieson family said there were "many questions that need to be answered", by organisations such as social services and the NHS, about how the pair came to be in a situation which ultimately led to her death.

They welcomed the review.

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Media captionIn a statement outside court, Melissa Mathieson's family paid tribute to her

During the trial, the jury was told Conroy strangled Miss Mathieson before attempting to drag her from her third-floor bedroom to his room on the second floor.

He was thwarted by staff who found Miss Mathieson injured on the stairs with red marks around her neck.

She died a few days later in hospital.

Admitted attack

After being arrested, Conroy told officers he was responsible and later admitted to the home's general manager that he had attacked Miss Mathieson.

Consultant psychologist John Sandford told the jury Conroy showed "from a young age abnormal sexual drive and a history of aggressive behaviour".

Speaking for the prosecution he said he believed Conroy suffered from paraphilia - a condition characterised by perverted or irregular sexual desires - and was fixated on strangulation and sex with dead women.

Dr Sandford said there was nothing to suggest he did not know what he was doing; something that was legally and morally wrong.

In defence, psychiatry professor Seena Fazel told the trial Conroy's "desire to have sexual relations overrode any other considerations".

The jury was told Conroy had an IQ of 62 and a "substantial impairment of judgment".

Mathieson family statement

"Melissa's death has left such a huge, huge hole in our lives. [She] did not have a nasty bone in her body; she was a gentle, kind and lovely girl.

"She always brought a bit of a challenge in all our lives, and things were quiet without her when she stayed at different places during her last 10 months.

"We keep thinking we are going to see her bound through the doors. But now that she is not here at all - it's the emptiness that is overwhelming.

"We know better than most people the difficulties that autism can present so our feelings about Jason Conroy are not based on ignorance of his condition.

"What he has done is awful; we cannot comprehend it. He has deprived a brother of his sister.

"He has deprived us parents of the privilege of watching our daughter to continue to blossom, thrive, grow up and have children of her own - because she would have got through her difficulties and gone on to have the future life that she wanted within the community.

Senior investigating officer Andrew Mott, of Avon and Somerset Police, said: "This was a desperately sad case in which a young person's life was cut tragically short.

"It has been a complex investigation which involved carrying out a number of psychiatric assessments on the defendant.

"I would like to pay tribute to Melissa's family who have shown the utmost support for the criminal investigation and legal process."

The Safeguarding Adults Board said the independent review would "fully explore all of the circumstances of this truly sad event" and would be reported to the board next year.